Keltham shall now observe to them that, if Meritxell has 12 green and prefers two blue to three green, and Gregoria has 12 blue and prefers two green to three blue, then all of the trades "5 green for 7 blue", "6 green for 6 blue", and "7 green for 5 blue", are mutually beneficial, but differently divide up the gains from trade.
There's a lot of different ways for jellychips to be arranged such that they can't be moved around without making at least one player worse off. For example, Meritxell could have all the chips, and nobody else could have any. Then any other way of arranging the chips will make Meritxell worse off! So that's one of the many possible global optima.
Different paths through the mutually beneficial trades will take you to different global optima. So long as all the trades are mutually beneficial, you won't end up worse off than if you never traded, at the end; but you might end up much worse off than if you'd traded more carefully.
Keltham is a bit surprised that they didn't more quickly see the way in which this game resembled real life, since they seem pretty good at mathematical comprehension of the sort of structure that this game has in common with real life. But that will come with having more than one day's practice with parsing up games and real life into the pure abstract structures and simple mathematical properties they have in common, to parse up real life as a shadow of Law that is then recognized at once when incarnated in some much simpler game.